FASTA format description

A sequence in FASTA format begins with a single-line description,
followed by lines of sequence data. The description line is
distinguished from the sequence data by a greater-than (">") symbol
in the first column. It is recommended that all lines of text be
shorter than 80 characters in length. An example sequence in FASTA
format is:

Sequences are expected to be represented in the standard
IUB/IUPAC amino acid and nucleic acid codes, with these
exceptions: lower-case letters are accepted and are mapped
into upper-case; a single hyphen or dash can be used to represent
a gap of indeterminate length; and in amino acid sequences, U and *
are acceptable letters (see below). Before submitting a request,
any numerical digits in the query sequence should either be
removed or replaced by appropriate letter codes (e.g., N for
unknown nucleic acid residue or X for unknown amino acid residue).
The nucleic acid codes supported are: